Biomedical subjects

Meng Wang

Publications and source records attributed to Meng Wang.

At least 37 records · Page 2Linked to original sources

PubMed2006

Statistical description of the free-space propagation of highly aberrated optical beams.

The free-space propagation of initially aberrated optical beams is considered with an emphasis on aero-optical applications. An exact statistical solution of the paraxial wave equation is derived that can be used to obtain statistics of the beam such as beam center, spread, and higher-order statistics as algebraic functions of propagation distance, wavelength, and statistics of the initial wavefront. Correlations between the proposed description and intensity-based statistics, such as the Strehl ratio, are investigated. It is found that the root-mean-square (rms) of the gradient of the wavefront plays an important role in causing coherence degradation and that the rms of the wavefront error is not always an appropriate measure of the degradation. To illustrate the use of this statistical tool, index of refraction data from a numerical simulation of compressible flow over a cylinder are employed to perform an aero-optical analysis.

Journal Article↗

PubMed2006

[A new method for visual SARS DNA sequences analysis].

Traditional DNA sequence analysis is based on sequence alignment, while a new DNA visual sequence analysis is proposed in this paper. Based on S. Wolfram's cellular automation theory, the method transfers one-dimensional DNA sequence into two-demensional visual image. Applying this method to SARS DNA sequence analysis, a characteristic of SARS-CoV differing from non-SARS is discovered. Compared with all known coronaviruses' images, It is found that this is a unique characteristic of SARS virus, and it is helpful to clinical identification of SARS.

Algorithms↗

PubMed2005

Low-frequency Fourier spectrum for predicting membrane protein types.

Cell membranes are vitally important to living cells. Although the infrastructure of biological membrane is provided by the lipid bilayer, membrane proteins perform most of the specific functions. Knowledge of membrane protein types often provides crucial hints toward determining the function of an uncharacterized membrane protein. With the avalanche of new protein sequences generated in the post-genomic era, it is highly demanded to develop a high throughput tool in identifying the type of newly found membrane proteins according to their primary sequences, so as to timely annotate them for reference usage in both basic research and drug discovery. To realize this, the key is to establish a powerful identifier that can catch their characteristic sequence patterns for different membrane protein types. However, it is not easy because they are buried in a pile of long and complicated sequences. In this paper, based on the concept of the pseudo-amino acid composition [K.C. Chou, PROTEINS: Struct., Funct., Genet. 43 (2001) 246-255], the low-frequency Fourier spectrum analysis is introduced. The merits by doing so are that the sequence pattern information can be more effectively incorporated into a set of discrete components, and that all the existing prediction algorithms can be straightforwardly used on such a formulation for protein samples. High success rates were observed by the re-substitution test, jackknife test, and independent dataset test, indicating that the low-frequency Fourier spectrum approach may become a very useful tool for membrane protein type prediction. The novel approach also holds a high potential for predicting many other attributes of proteins.

Fourier Analysis↗

PubMed2005

Acute toxicity of nano- and micro-scale zinc powder in healthy adult mice.

The purpose of this study is to evaluate the acute toxicity of oral exposure to nanoscale zinc powder in mice. The healthy adult male and female mice were gastro-intestinally administered at a dose of 5 g/kg body weight with two size particles, nanoscale zinc (N-Zn) and microscale zinc (M-Zn) powder, while one group mice treated with sodium carboxy methyl cellulose was used as the control. The symptoms and mortality after zinc powder treatment were recorded. The effects of particles on the blood-element, the serum biochemical level and the blood coagulation were studied after 2 weeks of administration. The organs were collected for histopathological examination. The N-Zn treated mice showed more severe symptoms of lethargy, vomiting and diarrhea in the beginning days than the M-Zn mice. Deaths of two mice occurred in the N-Zn group after the first week of treatment. The mortalities were confirmed by intestinal obstruction of the nanoscale zinc aggregation. The biochemical liver function tests of serum showed significantly elevated ALT, AST, ALP, and LDH in the M-Zn mice and ALT, ALP, and LDH in the N-Zn mice compared with the controls (P<0.05), which indicated that the liver damage was probably induced by both micro- and nano-scale zinc powders. The clinical changes were observed in the two treated group mice as well. The levels of the above enzymes were generally higher in the M-Zn mice than in the N-Zn mice, which implied that M-Zn powder could induce more severe liver damage than N-Zn. The biochemical renal function tests of serum BUN and CR in the M-Zn mice markedly increased either compared with the N-Zn mice or with the controls (P<0.05), but no significant difference was found between the N-Zn and the control mice. However, severe renal lesions were found by the renal histopathological examination in the N-Zn exposed mice. Therefore, we concluded that severe renal damage could occur in the N-Zn treated mice, though no significant change of blood biochemical levels occurred. Blood-element test showed that in the N-Zn mice, PLT and RDW-CV significantly increased, and HGB and HCT significantly decreased compared to the controls, which indicated that N-Zn powder could cause severe anemia. Besides the pathological lesions in the liver, renal, and heart tissue, only slight stomach and intestinal inflammation was found in all the zinc treated mice, without significant pathological changes in other organs.

Animals↗

PubMed2005

Evaluation of modifying collagen matrix with RGD peptide through periodate oxidation.

The aim of the study is to evaluate the effect of modifying collagen matrices with Arg-Gly-Asp (RGD) peptide through periodate oxidation. The collagen matrices were modified with RGD peptide, by periodate activation. The modified collagen matrices and unmodified matrices were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and electron spectroscopy for chemical analysis (ESCA). Mesenchymal stem cells (MSCs) were used to evaluate the cell compatibility of collagen matrices. In terms of cell growth, the MSCs attached much better on the modified matrix than on the unmodified one. But there was no significant difference between two groups regarding the MSC proliferation. Compared to the unmodified matrices, the mechanical strength of the modified matrix decreased sharply, and its 3D structure was destroyed. Introducing specific RGD receptor-mediated adhesion sites on matrices obviously enhanced the MSC adhesion on collagen matrices, but the coupled method of periodate oxidation would likely result in the declination of the mechanical strength of the matrix, as well as the destruction of the matrix structure. This would affect the cell growth on the matrix, and decrease the histocompatibility of the matrices.

Absorption↗

PubMed2005

Docosahexaenoic acid changes lipid composition and interleukin-2 receptor signaling in membrane rafts.

Polyunsaturated fatty acids, including docosahexaenoic acid (DHA, 22:6n-3), modulate immune responses and exert beneficial immunosuppressive effects, but the molecular mechanisms inhibiting T-cell activation are not yet elucidated. Lipid rafts have been shown to play an important role in the compartmentalization and modulation of cell signaling. We investigated the role of DHA in modulating the lipid composition in lipid rafts and membrane subdomain distribution of interleukin-2 (IL-2) receptor signaling molecules. We found that DHA altered lipid components of rafts and modified the IL-2-induced Janus kinase-signal transducer and activator of transcription (STAT) signaling pathway by partially displacing IL-2 receptors from lipid rafts. We fractionated plasma membrane subcellular compartments and discovered that certain amounts of STAT5a and STAT5b existed in detergent-resistant plasma membrane fractions of T-cells. After DHA treatment, STAT5a and STAT5b were not detected in lipid raft fractions and were located in detergent-soluble fractions. These data demonstrate for the first time that DHA alters the lipid composition of membrane microdomains and suppresses IL-2 receptor signaling in T-cells. Thus, our data provide evidence for a functional modification in lipid rafts by DHA treatment and explain PUFA-mediated immunosuppressive effects.

Cell Membrane↗

PubMed2005

Crystallin {gamma}B-I4F mutant protein binds to {alpha}-crystallin and affects lens transparency.

A new mouse mutant line, Clapper, identified from N-ethyl-N-nitrosurea (ENU)-mutagenized mice, develops a dominant lamellar cataract. The cataract blocks the image of retinal fundus and transmits a fuzzy fluorescein image of retinal vasculature during angiography. The cataractous lens opacity decreases as the mice age. The Clapper mutation has been identified to be a missense mutation of the gammaB-crystallin gene that replaces the 4th isoleucine residue with a phenylalanine (gammaB-I4F). Unlike wild type gammaB, the gammaB-I4F mutant protein binds to alpha-crystallin to form high molecular weight complexes in vivo and in vitro. Circular dichroism measurements indicate that gammaB-I4F protein is less stable than wild type gammaB at high temperature. Darkly stained aggregates, enlarged interfiber spaces, and disorganized and smaller inner mature fibers were found in the regions of the cataract in homozygous Clapper mutant lenses. Thus, the lamellar cataract is likely due to the light-scattering effects of the enlarged interfiber spaces and protein aggregates caused by gammaB-I4F mutant proteins interacting with alpha-crystallin in the lens.

Angiography↗

PubMed2005

Molecular characterization of the circulating anti-HIV-1 gp120-specific B cell repertoire using antibody phage display libraries generated from pre-selected HIV-1 gp120 binding PBLs.

Human bone marrow is a major repository for maturated antibody-secreting plasma cells, which produce the majority of the antibodies found in serum, making it an attractive source for generating human immune antibody libraries. Unfortunately, bone marrow is not always readily available and, although human immune libraries can be generated from circulating B cells, the low frequency of antigen-specific B cells in the circulation yield few monoclonal antibodies of interest. We used a pre-selection strategy to enrich for antigen-specific B cells prior to library generation, and applied this approach to evaluate, at a molecular level, the nature of the human anti-HIV-1 gp120 repertoire encoded by circulating B cells. IgG antibody phage display libraries were generated from HIV-1 seropositive individuals using either affinity-selected anti-gp120 IgG-bearing circulating B cells, predominantly exhibiting memory/activated B cell phenotype, or unselected PBMCs. These libraries were selected against HIV-1 gp120, resulting in isolation of a panel of gp120-specific antibodies. Whereas only 2 gp120-specific antibodies were retrieved from the non-pre-selected HIV-1 library, 9 gp120-specific antibodies were retrieved from the 10-fold smaller library generated from the pre-selected B cells, demonstrating the feasibility of the approach. The anti-gp120 antibodies derived from the circulating B cells of HIV-1 donors generally resembles those from bone marrow plasma cells with respect to epitope specificity, affinity and neutralization ability. They exhibit high affinity for gp120, are directed against a variety of epitopes, but rarely exhibit the ability to neutralize HIV-1.

Amino Acid Sequence↗

PubMed2005

SLLE for predicting membrane protein types.

Introduction of the concept of pseudo amino acid composition (PROTEINS: Structure, Function, and Genetics 43 (2001) 246; Erratum: ibid. 44 (2001) 60) has made it possible to incorporate a considerable amount of sequence-order effects by representing a protein sample in terms of a set of discrete numbers, and hence can significantly enhance the prediction quality of membrane protein type. As a continuous effort along such a line, the Supervised Locally Linear Embedding (SLLE) technique for nonlinear dimensionality reduction is introduced (Science 22 (2000) 2323). The advantage of using SLLE is that it can reduce the operational space by extracting the essential features from the high-dimensional pseudo amino acid composition space, and that the cluster-tolerant capacity can be increased accordingly. As a consequence by combining these two approaches, high success rates have been observed during the tests of self-consistency, jackknife and independent data set, respectively, by using the simplest nearest neighbour classifier. The current approach represents a new strategy to deal with the problems of protein attribute prediction, and hence may become a useful vehicle in the area of bioinformatics and proteomics.

Algorithms↗

PubMed2005

Using fourier spectrum analysis and pseudo amino acid composition for prediction of membrane protein types.

Membrane proteins are generally classified into the following five types: (1) type I membrane protein, (2) type II membrane protein, (3) multipass transmembrane proteins, (4) lipid chain-anchored membrane proteins, and (5) GPI-anchored membrane proteins. Given the sequence of an uncharacterized membrane protein, how can we identify which one of the above five types it belongs to? This is important because the biological function of a membrane protein is closely correlated with its type. Particularly, with the explosion of protein sequences entering into databanks, it is in high demand to develop an automated method to address this problem. To realize this, the key is to catch the statistical characteristics for each of the five types. However, it is not easy because they are buried in a pile of long and complicated sequences. In this paper, based on the concept of the pseudo amino acid composition (Chou, K. C. (2001). PROTEINS: Structure, Function, and Genetics 43: 246-255), the technique of Fourier spectrum analysis is introduced. By doing so, the sample of a protein is represented by a set of discrete components that can incorporate a considerable amount of the sequence order effects as well as its amino acid composition information. On the basis of such a statistical frame, the support vector machine (SVM) is introduced to perform predictions. High success rates were yielded by the self-consistency test, jackknife test, and independent dataset test, suggesting that the current approach holds a promising potential to become a high throughput tool for membrane protein type prediction as well as other related areas.

Amino Acids↗

PubMed2005

Study on modification of collagen with chondroitin sulfate on the microcosmic level.

To observe the changes during the process of modificating collagen with chondroitin sulfate (CS), a series of experiments was designed. Collagen scaffold was constructed by lyophilization. CS was attached into the scaffold through crosslinking. Solid-liquid phase separation method was used to shape 3D porous structure. Both kinds of scaffolds were investigated by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Electron Spectroscopy for Chemical Analysis (ESCA), Amino Acid Analyses (AAA), and so on for structures and characteristics. The results showed that CS could improve the properties of collagen both in biocompatibility and mechanical property. It increased the polar groups on the surface of scaffold and protected amino acid residues of collagen fiber. At the same time, the structure of scaffold became more regular because of the increase of polar groups. It was indicated that those were the real reasons for the improvement of modification.

Amino Acids↗

PubMed2005

Effect of tetrandrine on calcium-dependent tumour necrosis factor-alpha production in glia-neurone mixed cultures.

Tumour necrosis factor-alpha is believed to have a deleterious role in the pathophysiology of brain injury. Tetrandrine has protective effect on neuronal cells, however, the mechanisms involved in its action have not been clearly established. The aim of this study was to investigate the role of tetrandrine on calcium-dependent tumour necrosis factor-alpha production in glia-neurone mixed cultures. Glia-neurone mixed cultures were treated by addition of Ca2+ regulating agents for a period of 6 hr. Tetrandrine or/and TMB-8 were added 30 min. before the stimulation. The supernatant tumour necrosis factor-alpha levels were quantified by enzyme-linked immunosorbent assay. Exposure of lipopolysaccharide 10 and 100 ng/ml caused significant increase in tumour necrosis factor-alpha production respectively, with no alteration in cultures treated with 1 ng/ml lipopolysaccharide. Glia-neurone mixed cultures exhibited a marked elevation in tumour necrosis factor-alpha production after exposure to CaCl2, KCl, thapsigargin, BHQ and norepinephrine in the presence of lipopolysaccharide at 1 ng/ml respectively. Tetrandrine 0.3, 1, and 3 microM concentration-dependently reduced tumour necrosis factor-alpha production evoked by CaCl2 or KCl. Tetrandrine preincubation had no significant effect on the response to Ca2+-ATPase inhibitor thapsigargin or BHQ. Norepinephrine-induced tumour necrosis factor-alpha production was significantly reduced by tetrandrine and almost abolished by combination of tetrandrine and intracellular Ca2+ release inhibitor TMB-8. These results suggested that tetrandrine at a concentration of 0.3, 1, or 3 microM inhibited tumour necrosis factor-alpha production induced by Ca2+ entry in glia-neurone mixed cultures.

Alkaloids↗

PubMed2005

Anti-human immunodeficiency virus type 1 (HIV-1) antibodies 2F5 and 4E10 require surprisingly few crucial residues in the membrane-proximal external region of glycoprotein gp41 to neutralize HIV-1.

The conserved membrane-proximal external region (MPER) of human immunodeficiency virus type 1 (HIV-1) gp41 is a target of two broadly neutralizing human monoclonal antibodies, 2F5 and 4E10, and is an important lead for vaccine design. However, immunogens that bear MPER epitopes so far have not elicited neutralizing antibodies in laboratory animals. One explanation is that the immunogens fail to recreate the proper molecular environment in which the epitopes of 2F5 and 4E10 are presented on the virus. To explore this molecular environment, we used alanine-scanning mutagenesis across residues 660 to 680 in the MPER of a pseudotyped variant of HIV-1(JR-FL), designated HIV-1(JR2), and examined the ability of 2F5 and 4E10 to neutralize the Ala mutant viruses. The results show that the only changes to produce neutralization resistance to 2F5 occurred in residue D, K, or W of the core epitope (LELDKWANL). Likewise, 4E10 resistance arose by replacing one of three residues; two (W and F) were in the core epitope, and one (W) was seven residues C-terminal to these two (NWFDISNWLW). Importantly, no single substitution resulted in resistance of virus to both 2F5 and 4E10. Surprisingly, 8 out of 21 MPER Ala mutants were more sensitive than the parental pseudovirus to 2F5 and/or 4E10. At most, only small differences in neutralization sensitivity to anti-gp120 monoclonal antibody b12 and peptide T20 were observed with the MPER Ala mutant pseudoviruses. These data suggest that MPER substitutions can act locally and enhance the neutralizing activity of antibodies to this region and imply a distinct role of the MPER of gp41 during HIV-1 envelope-mediated fusion. Neutralization experiments showing synergy between and T20 and 4E10 against HIV-1 are also presented. The data presented may aid in the design of antigens that better present the MPER of gp41 to the immune system.

AIDS Vaccines↗

PubMed2005

Reproducibility of functional MR imaging: preliminary results of prospective multi-institutional study performed by Biomedical Informatics Research Network.

PURPOSE: To prospectively investigate the factors--including subject, brain hemisphere, study site, field strength, imaging unit vendor, imaging run, and examination visit--affecting the reproducibility of functional magnetic resonance (MR) imaging activations based on a repeated sensory-motor (SM) task. MATERIALS AND METHODS: The institutional review boards of all participating sites approved this HIPAA-compliant study. All subjects gave informed consent. Functional MR imaging data were repeatedly acquired from five healthy men aged 20-29 years who performed the same SM task at 10 sites. Five 1.5-T MR imaging units, four 3.0-T units, and one 4.0-T unit were used. The subjects performed bilateral finger tapping on button boxes with a 3-Hz audio cue and a reversing checkerboard. In a block design, 15-second epochs of alternating baseline and tasks yielded 85 acquisitions per run. Functional MR images were acquired with block-design echo-planar or spiral gradient-echo sequences. Brain activation maps standardized in a unit-sphere for the left and right hemispheres of each subject were constructed. Areas under the receiver operating characteristic curve, intraclass correlation coefficients, multiple regression analysis, and paired Student t tests were used for statistical analyses. RESULTS: Significant factors were subject (P < .005), k-space (P < .005), and field strength (P = .02) for sensitivity and subject (P = .03) and k-space (P = .05) for specificity. At 1.5-T MR imaging, mean sensitivities ranged from 7% to 32% and mean specificities were higher than 99%. At 3.0 T, mean sensitivities and specificities ranged from 42% to 85% and from 96% to 99%, respectively. At 4.0 T, mean sensitivities and specificities ranged from 41% to 73% and from 95% to 99%, respectively. Mean areas under the receiver operating characteristic curve (+/- their standard errors) were 0.77 +/- 0.05 at 1.5 T, 0.90 +/- 0.09 at 3.0 T, and 0.95 +/- 0.02 at 4.0 T, with significant differences between the 1.5- and 3.0-T examinations and between the 1.5- and 4.0-T examinations (P < .01 for both comparisons). Intraclass correlation coefficients ranged from 0.49 to 0.71. CONCLUSION: MR imaging at 3.0- and 4.0-T yielded higher reproducibility across sites and significantly better results than 1.5-T imaging. The effects of subject, k-space, and field strength on examination reproducibility were significant.

Adult↗

PubMed2005

A new nucleotide-composition based fingerprint of SARS-CoV with visualization analysis.

It has been observed by conducting an extensive analysis of the two-dimensional cellular automata images of known SARS-CoV genome sequences that the V-shaped cross-lines only exist in some special locations, and hence can be used as a fingerprint to identify the SARS sequences. Such a discovery can be used to rapidly and reliably diagnose SARS coronavirus for both basic research in laboratories and practical application in clinics.

Algorithms↗

PubMed2005

[Studies on the anticancer effects of total alkaloid from Viscum coloratum].

OBJECTIVE: To study the anticancer effects of total alkaloid from Viscum coloratum in vivo and vitro. METHOD: In vitro, MTT assays were used t o measure the inhibitory effect. Cells at period of logarithmic growth were incubated for 24 hours. Then total alkaloid of various concentrations were added. 24 hours later, supernatant was removed and MTT was added. 4 hours after that, DMSO was added, then 30 minutes later, A value was measured. In vivo, suspension of carcinoma cells was implanted in the mice's limbs subcutaneously, 0.2mL each. 24 hours later, the mice were grouped randomly. Fed by total alkaloid continuously for 7 days, the mice were sacrificed. The tumors were weighed and calculated the inhibitory rates. RESULT: In vitro, it shows that total alkaloid has prominent inhibitory effect on the growth of carcinoma cells. In vivo, it shows that total alkaloid can inhibit the growth of tumors and prolong the survival days of the mice bearing tumors. CONCLUSION: Total alkaloid from Viscum coloratum has the activities of anticancer.

Alkaloids↗

PubMed2005

[Clinical characteristics of bilateral primary breast cancer: a report of 100 cases].

BACKGROUND & OBJECTIVE: Women with breast cancer have an increased risk of new primary tumors of the contralateral breast. This study was to analyze the clinical characteristics of bilateral primary breast cancer (BPBC), and explore risk factors of BPBC. METHODS: Clinical data of 100 patients with BPBC and 200 patients with unilateral primary breast cancer (UPBC) were compared. RESULTS: The age of disease and age of menarche of BPBC patients were significantly younger than those of UPBC patients (P<0.05). Compared with UPBC patients, BPBC patients had a significantly greater prevalence of family history (15% vs. 5%, P<0.01); incidence rate of breast cancer before menopause was significantly higher in BPBC patients than in UPBC patients (70% vs. 58%, P<0.05). Pathologically positive rate of ipsilateral axillary lymph nodes was not significantly different between the 2 groups. The radiation treatment proportion in metachronous BPBC patients was not significantly different from that in UPBC patients (69% vs. 58%, P>0.05). CONCLUSIONS: Compare with UPBC patients, BPBC patients have a significantly greater prevalence of family history, and are younger. The estrogen might be closely related to BPBC, but the lymphatic metastasis ability of the first tumor in BPBC is similar to that of UPBC.

Adult↗

PubMed2004

Mercury and trace element distribution in organic tissues and regional brain of fetal rat after in utero and weaning exposure to low dose of inorganic mercury.

Since it is still absent data about the toxic risk of low dose, especially an environmentally relevant dose of mercury to fetus after their prenatal exposure, this present work was designed to investigate the metabolism of Hg and its effect on the levels of essential trace elements in the organic tissues and the brain regions of infant rats after their exposure to environmentally relevant low dose of Hg(II) during the whole pregnant and weaning period. The pregnant female rats were exposed to a very low dose of 0.2 microg Hg2+/ml (as HgCl2, 12 rats/group) in drinking water from prenatal day 0 continued to postnatal day 20. The contents of Hg and other elements (Cu, K, Mg, Mn, Na, Ca, Co, Fe, Se and Zn) in the liver, kidney, heart, spleen, pancreas and the brain regions (cerebrum, cerebellum, brain stem, hippocampus, thalamus and the remains) of the maternal and their infant rats were determined. The highest Hg contents were found in kidney of both maternal and infant rats. Considering the percentage of Hg accumulation, approximately 52.7%, 38.7%, and 1.66% were found in kidney, liver and brain for maternal rats, respectively, while 23.7%, 48.9% and 15.6% for infant rats. The important findings in this work were that the low dose of inorganic mercury appeared to accumulate in the brain of offspring and more Hg was present in infant brain than in their mother. As in the brain regions, the highest Hg content was present in infant hippocampus and cerebellum, whereas the Hg contents in maternal brains varied not so much. The imbalances of Fe/Cu, Cu/Zn, Zn/Se mass ratios and the molar ratios of Hg over other elements in the Hg-exposed rats were observed.

Administration, Oral↗